Conventionally, a sealing agent for tire punctures has been proposed in which an acrylic emulsion and/or a fatty acid salt having from 9 to 18 carbons among surfactants is used as a base of a stabilizer for a natural rubber latex in place of ammonia in order to prevent the solidification of the natural rubber latex in a valve and suppress the generation of irritating odors without lowering sealing performance below a necessary standard level. In this sealing agent for tire punctures, an acrylic emulsion and/or a fatty acid salt having from 9 to 18 carbons among surfactants is added to a mixed liquid (in which terpene resin as a tackifier and ethylene glycol as an antifreezing agent are added to a natural rubber latex) as a stabilizer for stabilizing the natural rubber latex (Patent Document 1).